The first problem of this experience is
to extract caffeine. This tutorial will bring you
help for the caffeine extraction experiment

Warning : Caffeine is a toxic substance.
The letal dose is only 5g. Therefore,
when you extract caffeine don't go
drip the bottom of your balloon flask, ok ?
Other thing, you are going to use some
solvents for the extraction. These solvents
are therefore dangerous so doesn't drink the
coffee of which you extracted caffeine.
In conclusion you don't have to put anything
in your mouth !

Important

- Closed blouse
- protective glasses
- Gloves
- hood

Materials

50g of thin coffee
calcium carbonate CaCO3
magnesium sulfate or anhydrous sodium or also anhydrous calcium chloride
Dichloromethane or chloroform
Water
decantation funnel
cooler
Two-neck round bottom flask
balloon flask heater
Stirring rod
Bath of oil
filtering flask
Erlenmeyer of 100ml

Process

Equip your glass balloon with the cooler
weigh 50g of coffee and place it in the ball
Add 300ml of water
Add 12g of calcium carbonate
Open the water tape connected to the cooler
Agitate and heat
When the reflux begins to heat for 2 hours

go drink a cola not a bierre ok ?
Filter the brown juice on the filtering flask
Let cool !!!
Decant the brown juice in a decantation funnel
Add 50ml of dichloromethane (or chloroform)
Agitate manualy
Let decantRecovers the organic phase
Add 50ml of dichloromethane in the decantation funnel
Agitate manually
Let decant
recover the organic phase
Regroup the 2 organic phases (colorful solutions)
It is preferable to keep the aqueous phases until the end of the experience.
Go drink a cola you have worked well !
Dry the organic phase with the calcium carbonate.
Filter the organic solution with the help of a funnel containing a tip of cotton (see picture)

Recover the juice and evaporate the solvent under low pressure

The bottom of your balloon glass has a powder, it is pure caffeine. You can do a recristallisation of caffeine. If you have some problems/questions don't hesitate to contact me.

Explanations

Why do we have to heat water at the step of the extraction ?

Caffeine is very soluble in hot water (455g/l to 65°C) and little soluble in cold cold (22g/l to 25°C). So to extract the maximum of caffeine we use hot water.

what is the function of calcium carbonate?

It permits to basify the solution. But why ? In hot water, we extract caffeine, but also water soluble acidic tannins, the chlorogenic acid and pigments. In the proposed experience, the calcium carbonate basify the solution and permits to ionize all these undesirable molecules. At the step of the liquidate-liquid extraction (water-dichloromethane), the anions coming from acids (undesirable molecules) remain preferentially in the basic aqueous solution, caffeine passes in the organic phase.